In construction, and other applications, it is often important to know the vertical displacement between two or more selected and spaced locations. Typically, such vertical displacements are determined by the use of a tripod, surveyor's level, and rod which are used in a conventional manner to detect vertical displacements between a reference point and a selected and spaced location. Measurements of this type are labor intensive operations and require a considerable amount of training. Furthermore, it is not uncommon for inaccurate measurements to be taken, especially if the operator is insufficiently or improperly trained. These inaccurate measurements can cause serious structural defects in the resulting structures.
As a potential solution to this problem, numerous liquid leveling systems have been developed in the past. While these leveling systems, as a general rule, incorporate one or more liquid containing members, the systems generally are designed to provide a representation of whether two points are level, one with respect to the other. Additionally, these leveling systems generally require that the surface upon which the reference point is placed is perfectly level in order to properly calibrate the leveling system. A perfectly level surface is generally not available on construction sites and other remote and rugged locations. Finally, these leveling systems are generally able to detect the vertical displacement between only two selected and spaced locations, whereas it is preferable to be able to detect the vertical displacement between a plurality of selected and spaced locations. Various examples of leveling and measuring systems are found in U.S. Pat. Nos. 4,087,920 to Huggert et al.; 4,686,773 to Brewer; 4,972,596 to Brewer; and 4,991,302 to Brewer, the entire disclosures of which are hereby incorporated by reference.
Therefore, what is needed is an apparatus for measuring the vertical displacement between a plurality of selected and spaced locations on a variety of surfaces.